Project Summary Acute HIV infection (AHI) is the period from HIV transmission until antibodies develop and during which unimpeded viral replication results in extremely high viral loads in the blood and genital secretions. Accordingly, the probability of transmission during unprotected intercourse with AHI is very high; an estimated 43% of all new HIV infections in the US are transmitted by persons with AHI. This has critical public health implications since individuals with AHI are likely to continue engaging in high-risk behaviors that led to recent HIV acquisition, particularly if they do not know they are infected. As such, identifying individuals with AHI provides a critical opportunity to avert a significant number of onward transmission events. While the Internet has clearly been shown to be a high risk environment for MSM, a group that accounts for over 50% of new HIV infections in the US and 56% of AHI cases in North Carolina (NC), its use as a complement to traditional partner notification has not been fully explored. The current NC strategy to detect AHI using pooled HIV RNA testing on seronegatives is effective, but the disadvantages of this strategy include high cost and a prolonged time from testing to confirmed AHI diagnosis due to technical aspects of 3rd generation serum EIA testing and the HIV RNA pooling strategy. To overcome such logistical and cost challenges and the delay from screening to AHI diagnosis, this cross-sectional study will implement a novel a 4th generation EIA assay, which simultaneously detects HIV-1/2 antibodies and p24 antigen, thereby decreasing the seroconversion window period and detecting the pre-seroconversion presence of p24 antigen. The study will compare the performance, cost-effectiveness, and rapidity of a 4th generation EIA to other HIV diagnostic assays to diagnose AHI. Study data will be used to evaluate the potential cost savings and ability to detect AHI earlier with the use of new testing strategies, with critical implications for the use of newer HIV antibody assays in publicly funded HIV testing sites and secondary prevention. Several studies, including our own, indicate that familiarity with and access to the Internet provides opportunities for MSM to meet sex partners and engage in high risk behaviors. The lack of partner information has been shown to limit the ability to completely perform partner notification by traditional means. This study will incorporate enhanced partner tracing with a novel Internet intervention and determine its feasibility, cost-effectiveness and yield in increasing the notification, screening and treatment of partners of acutely infected patients. The use of internet technologies for partner notification will also include real-time linkage to information on HIV testing sites for AHI, symptoms associated with AHI and referral to HIV and STD care.